A cylindrical metal rod of length L0 is shaped into a ring with a small gap as shown. On heating the system -
x decreases, r and d increase
x and r increase, d decreases
x, r and d all increase
Data insufficient to arrive at a conclusion
No matter how detailed this question looks, the simple answer is - everything within an object will expand, if the object itself expands. On heating, x, r and d must all increase.